Our road signs are as much a part of Britain’s landscape as the Union Jack and the London bus. Drive on any major road and the green and blue signs with their rounded white typeface are unmissable. Turn off onto a smaller road and you’ll immediately encounter the familiar red-bordered circles and triangles with their black silhouetted figures. Margaret Calvert played a role in designing all of these signs.

Born in South Africa in 1936, Calvert moved to Britain as a teenager and went on to study at the Chelsea College of Art. There, she met tutor and designer Jock Kinneir. In 1957, Kinneir won the commission to design the signs for the new Gatwick Airport and he hired Calvert, then just 21, as his assistant.

The Fifties were a boom time for Britain’s roads: more and more people were driving and many new roads were being built. However, the signage was a mess – a jumbled mismatch of signs commissioned by different bodies with no consistency. When Kinneir was appointed head of signs for Britain’s roads, Calvert joined his team. Together they embarked on a momentous feat of design: creating a rigorous system of shapes, colours and typefaces, first for the brand new M1 motorway, which opened in 1959, then for signs (rolled out in the early Sixties) across the entire country’s network of roads.

Motorway signs, says Calvert, were made sky blue because it was a colour that fitted well in the landscape. Signage on A-roads was picked out in a carefully chosen shade of harmonious green (a compromise between the colour that Kinneir and Calvert wanted and the darker ‘smoking jacket’ green preferred by a Civil Service official). They created two clear sans-serif typefaces, Transport and Motorway, to replace existing fonts which were difficult to read at speed.

Kinneir and Calvert’s innovations also included a branched line to denote junction layouts from the driver’s point of view and keeping information to the bare minimum. Calvert was specifically in charge of the human and animal images, and came up with a now iconic set of deceptively simple black pictograms on white backgrounds for hazards such as ‘farm animals’ and ‘school crossing’. The picture on the latter of a girl leading a small boy by the hand replaced an older one where a boy was leading a girl. Calvert later disclosed that the girl in the new sign was based on a photo of herself as a child.

In 1964, Calvert became a partner in the practice. Over the next 20 years, Kinneir Calvert Associates created designs for institutions including British Rail, the NHS, BAA and the army. Calvert created an eponymous typeface, ‘Calvert’, and took up teaching the next generation: she was head of graphic design at the Royal College of Art until 1991. Dubbed ‘a house style for Britain’, the innovative designs she helped to create changed the face of the country forever.

The Forgotten Women series is part of Stylist’s Visible Women campaign, dedicated to raising the profiles of brilliant women past and present. Find out more about the campaign here, and see more Visible Women stories here.

Main illustration: Josie Jammet. Image: Getty Images